When using a Python that has not been installed to build 3rd-party

modules, distutils does not understand that the build version of the
source tree is needed.

This patch fixes distutils.sysconfig to understand that the running
Python is part of the build tree and needs to use the appropriate
"shape" of the tree. This does not assume anything about the current
directory, so can be used to build 3rd-party modules using Python's
build tree as well.

This is useful since it allows us to use a non-installed debug-mode
Python with 3rd-party modules for testing. It as the side-effect that
set_python_build() is no longer needed (the hack which was added to
allow distutils to be used to build the "standard" extension modules).

This closes SF patch #547734.

Lib/distutils/sysconfig.py

@@ -23,19 +23,20 @@ from errors import DistutilsPlatformError
 PREFIX = os.path.normpath(sys.prefix)
 EXEC_PREFIX = os.path.normpath(sys.exec_prefix)
 
-# Boolean; if it's true, we're still building Python, so
-# we use different (hard-wired) directories.
-
-python_build = 0
-
-def set_python_build():
-    """Set the python_build flag to true.
-
-    This means that we're building Python itself.  Only called from
-    the setup.py script shipped with Python.
-    """
-    global python_build
+# python_build: (Boolean) if true, we're either building Python or
+# building an extension with an un-installed Python, so we use
+# different (hard-wired) directories.
+
+argv0_path = os.path.dirname(os.path.abspath(sys.executable))
+landmark = os.path.join(argv0_path, "Modules", "Setup")
+if not os.path.isfile(landmark):
+    python_build = 0
+elif os.path.isfile(os.path.join(argv0_path, "Lib", "os.py")):
     python_build = 1
+else:
+    python_build = os.path.isfile(os.path.join(os.path.dirname(argv0_path),
+                                               "Lib", "os.py"))
+del argv0_path, landmark
 
 
 def get_python_inc(plat_specific=0, prefix=None):
@@ -53,7 +54,14 @@ def get_python_inc(plat_specific=0, prefix=None):
         prefix = plat_specific and EXEC_PREFIX or PREFIX
     if os.name == "posix":
         if python_build:
-            return "Include/"
+            base = os.path.dirname(os.path.abspath(sys.executable))
+            if plat_specific:
+                inc_dir = base
+            else:
+                inc_dir = os.path.join(base, "Include")
+                if not os.path.exists(inc_dir):
+                    inc_dir = os.path.join(os.path.dirname(base), "Include")
+            return inc_dir
         return os.path.join(prefix, "include", "python" + sys.version[:3])
     elif os.name == "nt":
         return os.path.join(prefix, "include")
@@ -163,7 +171,7 @@ def get_config_h_filename():
 def get_makefile_filename():
     """Return full pathname of installed Makefile from the Python build."""
     if python_build:
-        return './Makefile'
+        return os.path.join(os.path.dirname(sys.executable), "Makefile")
     lib_dir = get_python_lib(plat_specific=1, standard_lib=1)
     return os.path.join(lib_dir, "config", "Makefile")
 

setup.py

@@ -822,5 +822,4 @@ def main():
 
 # --install-platlib
 if __name__ == '__main__':
-    sysconfig.set_python_build()
     main()